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ATEL # 1859; J.L. Galache, M.R. Garcia, M.A.P. Torres, S.S. Murray (CfA), D. Steeghs (U. of Warwick/CfA) and B.F. Williams (U. of Washington)
on 4 Dec 2008; 1:47 UT
Password Certification: Jose Luis Galache (email@example.com)
Subjects: X-ray, Binaries, Black Holes, Neutron Stars, Pulsars, Transients
Referred to by ATEL #: 1870
We report the discovery of a previously unseen X-ray source detected in a 5ks Chandra/ACIS observation starting on 2008-11-27.72 UT as part of our ongoing Chandra/HST M31 transient program. Its coordinates (subject to the standard boresight correction) are RA(J2000) 00:42:45.96, Dec(J2000) +41:10:36.60, with centroiding errors of 0.18" and 0.21", respectively. It is therefore identified as CXOM31 J004245.9+411036.
Its spectrum is well described by an absorbed power law with Γ = 1.8 and nH = 2.4e21 atoms/cm2. The luminosity in the 0.3-8 keV range is 5.0e37 erg/s, with no photons having been detected above 3 keV.
The presence of a soft component suggests that this new transient may be a black hole transient in the hard state, although the power law does not rule out the possibility of it being a neutron star transient.
During this same observation, SWIFT J004320.5+411528 (Pietsch et al. 2008, ATel #1674; Galache et al. 2008, ATel #1693) was in the field of view of ACIS-I. We do not detect it above our limiting luminosity of ~5e35 erg/s. It was last observed to be active on 2008-10-21 (Henze et al. 2008, ATel #1806). We present a table with the known observations of this transient and its X-ray luminosities.
|Date (UT)||Lx (×1e38 erg/s)|